Description: 【Design】: The bike crank arm bolt features a hollow integrated chainring screw design, used for securing the crank and chainring's arm. It is an essential component of your bike's performance 【Quality material】: This m15 bicycle crankset bolt is made from quality aluminum alloy, ensuring durability and resistance to wear and tear. Its sturdy construction prevents deformation, allowing for long term use 【Easy installation】: This bike crankset screw is easy to install, making it a great replacement for damaged or old parts on your bicycle 【Appropriate size】: With an inner diameter of 15 mm, a length of 2.5 cm, and a width of 2.1 cm, this cycling accessory is compact in structure and lightweight in design, nice for portability 【Wide application】: This bikes hollow fixing is ideal for various types of bikes such as mountain bikes and road bikes among others; it also makes a practical accessory tool gift for cycling enthusiasts Specification: Material: Aluminum Alloy Size Chart: Total Size: 2.1 cmx2.1 cmx2.5 cm/0.83 inchx0.83 inchx0.98 inch Inner Diameter: 1.5 cm/0.59 inch Package Includes: 1 Bike Crank Arm Bolt(4 Pack) Note: Please allow slightly errors 1-2cm differences due to manual measurement.